Process for production of bronze alloys



United States Patent PROCESS FOR PRODUCTION OF BRONZE ALLOYS ArthurGeorge Gardner, methwick, near Birmingham,

and Thomas Stott Lister, Handsworth Wood, Birmingham, England, assignorsto Wickman Limited, Coventry, England No Drawing. Application January14, 1954;

Serial No. 404,122

i Claims priority, application Great Britain January 29, 1956 2 Claims.(Cl. 75-72) This invention relates to bronze alloys of a brittlecharacter, and particularly such as are used as the bonding material in,for example, the manufacturing of grinding wheels containing diamond orother hard particles as the abrasive constituent.

For the above mentioned purpose it is essential that the bonding alloyshall be uniformly brittle, in order to permit release of the abrasiveparticles which have become dulled by wear, the release being effectedby the crushing action exerted on the wheel when in normal use.

The object of the invention is to enable the above mentioned requirementto be met in a more satisfactory manner than heretofore.

The invention consists of a bronze alloy made from (essentially) copperand at least sufficient tin to produce an alloy having a proportion ofdelta phase, both the copper and the tin being in a powdered condition,and the tin, or both the tin and copper being initially in the oxideform, the alloy being produced by simultaneous reduction and alloying ofthe powdered constituents at a temperature below the melting point ofthe resultant alloy.

In one example, copper oxide derived from electrolytically preparedcopper powder and fully oxidised, is comminuted in a ball mill and mixedwith powdered tin oxide of good commercial grade, in the proportion inwhich the tin constituent is about 20% by weight of the combined copperand tin. The mixed powders are then placed in a loosely packed conditionin a heat-resisting container, and are heated in a reducing atmospherefor about two hours at a temperature of about 500 C. This results inreduction and alloying of the constituents. The alloy is then allowed tocool to room temperature in the reducing atmosphere.

Owing to the simultaneous reduction and alloying of the constituents,the delta phase on which the brittleness depends is uniformlydistributed throughout the final 2,768,891 Patented Oct 30, 1956 squareinch to the desired form. Subsequently it is sintered at 500 C. in areducing atmosphere. When the mixture has attained this temperature, itis transferred quickly to a press in which it is subjected to a pressureof from 8-30 tons per square inch. If desired any other hard abrasivematerial may be used instead of diamond.

Although it is preferred to use copper oxide and tin oxide of thequality mentioned this is not essential, as some degree of impurity ofeither constituent may be permissible. Further the extent to which theoxides are comminuted is not a critical condition.

In another example, powdered copper in the metallic state, and powderedtin oxide are treated in the manner above described, the final producthaving similar qualities to those of the first example.

The product obtained by the invention possesses the delta phase in auniformly distributed condition, and is uniformly brittle.

The degree of brittleness can be varied by varying the proportion of tinto vary the amount of delta phase metal present in the product, but toensure brittleness the proportions of tin oxide used should besufficient for the bronze alloy to contain from 10-30% by weight of thetin constituent.

Whilst the invention is especially applicable for use in the manufactureof abrasive wheels, it may be applied to other uses where uniformity ofbrittleness is required.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent is:

1. A process for producing a bronze alloy from copper and at leastsuflicient tin to produce in the alloy a proportion of delta phase,consisting in comminuting copper oxide derived from electrolyticallyprepared copper powder, mixing the comminuted copper oxide with powderedtin oxide in the proportion in which the tin constituent is from 10-30%by weight of the combined copper and tin constituents, and heating themixture in a reducing atmosphere for about two hours at a temperature ofabout 500 C. to elfect simultaneous reduction and alloying of theconstituents.

2. A process for producing a bronze alloy from copper and at leastsufficient tin to produce in the alloy a proportion of delta phase,consisting in mixing powdered copper in the metallic state with powderedtin oxide in the proportion in which the tin constituent is from 10- 30%by weight of the combined copper and tin constituents, and heating themixture in a reducing atmosphere for about two hours at a temperature ofabout 500 C. to effect simultaneous reduction and alloying of theconstituents.

References Cited in the file of this patent UNITED STATES PATENTS1,829,635 Davey Oct. 27, 1931 2,645,573 Drapeaw et al July 14, 1953FOREIGN PATENTS 3,962 Great Britain of 1874

1. A PROCESS FOR PRODUCING A BRONZE ALLOY FROM COPPER AND AT LEASTSUFFICIENT TIN TO PRODUCE IN THE ALLOY A PROPORTION OF DELTA PHASE,CONSISTING IN COMMINUTING COPPER OXIDE DERIVED FROM ELECTROLYTICALLYPREPARED COPPER POWDER, MIXING THE COMMINUTED COPPER OXIDE WITH POWDEREDTIN OXIDE IN THE PROPORTION IN WHICH THE TIN CONSTITUENT IS FROM 10-30%BY WEIGHT OF THE COMBINED COPPER AND TIN CONSTITUENTS, AND HEATING THEMIXTURE IN A REDUCING ATMOSPHERE FOR ABOUT TWO HOURS AT A TEMPERATURE OFABOUT 500*C. TO EFFECT SIMLTANEOUS REDUCTION AND ALLOYING OF THECONSTITUENTS.